Among various voice synthesis technologies that have been proposed recently, there are included the following examples: a technology for synthesizing and outputting a voice corresponding to a user's speech tone or vocal characteristics, the object of which is to make the resulting voice more human sounding (for example, refer to Patent Document 1); and a technology for analyzing a user's voice and thereby diagnosing a psychological or physical condition of the user (for example, refer to Patent Document 2). There is also proposed an interactive voice system for use in recognizing a voice inputted by a user, and for voice-synthesizing and outputting scenario-specified content to enable voice interaction to be carried out with the user (for example, refer to Patent Document 3).